According to German paranormal news website Grenzwissenschaft-aktuell, the documents will reveal sightings of UFOs over almost five decades, from the 1970s, and be published by the National Archives.

Alien hunters hope the files will show a number of high-profile incidents have been covered up, including an alleged UFO sighting in Rendlesham Forest in 1980, dubbed ‘Britain’s Roswell.’

A number of servicemen reported seeing lights in the forest near RAF Bentwaters and RAF Woodbridge. The disputed sightings, which are said to have lasted for three nights in December of that year, occurred when Britain was on high alert during the Cold War.

At the time, the Ministry of Defence (MoD) said the event posed no threat to national security, and it was therefore not investigated.

The secret papers were meant to be released in 2013, but 18 documents were withheld.

The latest publication date was set for March this year, but that date passed with no information given.

A spokesperson for the National Archives told Grenzwissenschaft-aktuell: “Due to the upcoming election here in the UK and the rules relating to the government departments during the pre-election period, the files will not be released until after the election.”

Speaking to the Daily Mail, Nick Pope, who worked for the MoD investigating UFO sightings until 2009, said: “There’s no smoking gun in these files that will confirm the existence of aliens, but there are plenty of fascinating UFO reports and MoD policy documents, so these really are the real-life X-Files.

“The delay has been a comedy of errors though, I think it’s more bureaucracy than conspiracy.”